I Recently asked a question to Dinonine-https://dinonline.org/2020/06/24/birkas-kohanim/
If one is next to a sefard minyan that does Birkas Kohanim should he or could he go listen even if he will miss a kadish or kedusha of uva letziyon?
There is no obligation to answer kaddish etc. to other minyanim while you are davening, if you want you may. However if it is going to hinder your davening, i.e. you will miss kedusha, etc. or even it merely hinders your concentration, you shouldn’t answer to it.
Halichos Shlomo (Tefilla) 6-12, ftnt. 42-43. Orach Neeman 109-12.
It seems the question was misunderstood. The question was specifically about birkas kohanim that there is a kiyum mitzvah deoraysa according to the charedim (brought in biur halacha) and does that override missing a kadish or kedush in the minyan you are presently in or not. Answering kaddish to a different minyan is a different question.
The answer will apply even to Birkas Kohanim, and even though it is a d’orayso. This is because right now he is davening where he is, and he is in middle of doing one mitzva, he is exempt from doing other mitzvos. Especially if it is going to diminish the mitzvah that he is presently doing.